Underlined word in ‘After lunch let’s go for coffee’ (for):

The word "for" in the sentence "After lunch let's go for coffee" functions as a preposition. A preposition is a word that shows the relationship between a noun or pronoun and other words in a sentence, often indicating direction, time, place, or purpose. Here, "for" indicates the purpose or destination of going, connecting "go" with "coffee".

• Adverb is incorrect because adverbs modify verbs, adjectives, or other adverbs, and "for" is not doing that here.
• Noun is incorrect as "for" is not a person, place, thing, or idea.
• Adjective is incorrect because adjectives describe nouns, and "for" does not describe any noun in the sentence.